A home base station, as a small scale base station installed at home or in office area, is called a home NodeB (HNB) in the 3rd generation (3G) mobile communication system and a home eNodeB (HeNB) in a long term evolution (LTE) system, and can be simplified as H(e)NB for both. In order to reduce the effect to a core network (CN), a home base station gate way is introduced in the home base station system, which is called HNB GW in the 3G system and H(e)NB GW in the LTE system.
As shown in FIG. 1, the HNB and the HNB GW in the 3G system are network elements in a access network, while serving GPRS (general packet radio service) supporting node (SGSN) and gateway GPRS supporting node (GGSN) are network elements in the CN. The interface between the wireless access network and the core network inherits from the interface between a macro base station and the core network and is also an Iu interface whose physical connection exists in the home base station gate way. From a logical point of view, an application layer protocol of the Iu interface is that a radio access network application part (RANAP) might be distributed in the home base station or the home base station gate way or both, and control messages between the SGSN and the GGSN that are the network elements in the core network use a GPRS tunneling protocol-control (GTP-C) signaling.
As shown in FIG. 2, the HeNB and the HeNB GW in the LTE system are network elements in the access network, while a mobility management entity (MME), a serving GW and a packet data network gateway (PDN-GW) are network elements in the core network. The interface between the wireless access network and the core network inherits from the interface between the macro base station and the core network and is also a S1 interface whose physical connection exists in the home base station gate way. From a logical point of view, the S1 interface application layer protocol is S1-AP (S1 application part) that might be distributed in the home base station or the home base station gate way or both, and control messages between the MME and the Serving GW, as well as between the Serving GW and the PDN-GW that are the network elements in the core network use the GTP-C signaling.
For normal mobile services, a mobile terminal (user equipment, UE) initiates a service process via the home base station, and this process has a little distinction from a service process via the macro base station. As shown in FIG. 1, in the 3G system, the procedure for the mobile terminal initiating a data service comprises: after the UE accesses the SGSN, the UE sends a packet data protocol (PDP) context activation request to the SGSN, and the request carries an access point name (APN) of the mobile terminal, that is because for different access points the SGSN might select different GGSN to access. The SGSN acquires address information of the corresponding GGSN node from a database or a server according to the acquired APN of the mobile terminal, and sends a context setup request to the corresponding GGSN; and the GGSN returns a context setup response, then the SGSN returns a PDP context activation acknowledgement to the UE to set up a route between the MS and the GGSN, so as to transmit packet data.
The home base station is a part of a public land mobile network (PLMN), and it can provide general mobile services for the mobile terminal user; meanwhile, the home base station is a part of the home internal network, so it also should provide the service of accessing the home network for the mobile terminal. Since the home base station already connects to the Internet, for pure surfing service, there is no need to access the Internet via the PLMN core network, and the mobile terminal can directly access the Internet via the home base station completely. Based on the above demands, the 3rd Generation Partnership Project (3GPP) proposed local IP access to provide a method for accessing the home network and directly accessing the services in the Internet via the home base station for the mobile terminal user.
According to the requirements of 3GPP, for all the mobile terminal users that are allowed to access the home base station, the local IP function can be used (on the premise that an operator agrees), that is because the implementation scheme has to not change functions of the mobile terminal users. In one implementation, i.e., when the home base station integrates a part of GGSN functions to work as a local GGSN, for a special APN, the mobile terminal indicates to use a local network access function by selecting the APN. According to the existing method, when the SGSN receives the APN including indicating the local access, the SGSN needs to acquire the address of the local GGSN according to the APN and initiate a bearer setup procedure to the local GGSN. Since the home base station is a user equipment, its address information is not included in a network planning range by the operator or its maintenance cost is extremely high. In this condition, the network elements in the core network cannot directly acquire the IP address of the home base station just according to the APN so as to initiate the bearer setup procedure to the local GGSN bond to the home base station, which is also the problem existing in the LTE home base station system so that the mobile terminal cannot access the local network via the home base station.